Congratulations!!! After reading your qualifications and potential itinerary, I am glad to inform you that you are practically OVERQUALIFIED to operate ANY vessel up to 60 feet offered by the various charter companies,subject to a small credit card hold for a damage deposit. <img src="http://www.traveltalkonline.com/forums/images/graemlins/Yikes.gif" alt="" />

Seriously, look for something around 17-21' feet long.Certainly big enough to go to Jost,Sandy Cay,etc. The seas can change pretty dramatically and things sometimes aren't(or are) as close as they look. The North side of Tortola can get some pretty impressive swells in March. Check with King,Island Time as you mentioned. Probably looking at 275+/- day plus fuel.